Manufacture of unchilled metallic castings by the centrifugal casting process



Oct. 12, 1937. w. RIDLEY ET AL 13 l MANUFACTURE OF UNCHILLED METALLIC CASTINGS BY THE CENTRIFUGAL CASTING PROCESS Filed Oct. 19, 1935 I 3 Sheets-Sheet l vvvvvvvvv v vvvvvvvvvvvvvvvvvvvvvv w. RIDLEY ET AL 2,095,575 MANUFACTURE OF UNCHILLED METALLIC CASTINGS BY THE CENTRIFUGAL CASTING PROCESS Filed Oct. 19, 1935 :s Sheets-Sheet 2 Oct. 12, 1937.

m m O QU D G O O O Q U U W Q 0 O U U |I|m|1|1|||11|||||||| 0 000 0 0000 000 000 00 0 0 0 0 0 0 0 0 0 0 OOOOOOOOOOOOOOOOO OQOOOOOOOO OO00OOO000O00000000000oooooV 0 l lolbllnllflbiololollpl llol Ip blml m ll l0 lpl l| J -QAJ Get. 12, 1937. w. RIDLEY ET AL I METALLIC CAS GS MANU TURE OF UNCHILLED THE CENTRIFUGAL CASTING PROCE'S Filed Oct. 19, 1935 3 Sheets-Sheet 3 g i i w W RIX/C'y 9 H )4 s Patented 0a. 12, 1937 UNITED STATES MANUFACTURE OF UNCHILLED METALLIC CASTINGS BY THE CENTRIFUGAL CAST- ING PROCESS William Rldley, Beeston, Nottingham'and Percy Hutchinson Wilson, Nottingham, England Application October 19, 1935, Serial No.

In Great Britain June 19, 1935 'lClalms.

This invention relates to the manufacture of unchilled metallic castings by the centrifugal casting process wherein use is made of dry pulverulent materials which are introduced into the mould- Just prior to the introduction of the molten metal so as to produce a film or lining on the interior surface of the mould for the purpose of preventing the chilling of the casting therein. Various powdered materials have been employed to that end and satisfactory results are known to have been obtained particularly by the use of ferrosilicon' or aluminium or a substance including aluminium in metallic form.

The introduction of the powdered material into the mould has also been practised invarious ways including among others a method of blowing the powdered material against the mould interior with the aid of compressed air or feeding it into the mould by means of a feed worm operating within a receptacle surrounding the casting trough. The main effort connected with all known methods so far in use has been directed to the provision of means enabling the film or lining produced within the mould to be uniform and reliable in every respect, failing which faulty castings and considerable waste have been found to result.

In order to attain this object use is made in acordance with this invention of a spiral conveyor or feed worm coupled with means adapted to ensure automatic supply thereto of the powdered material employed for successive casts in definitely reliable and arbitrarily variable quantitles and to maintain the feed of the powdered material thereto from the supply tank or feed box constant in every respect.

To this end the spiral conveyor adapted to be driven preferably from a separate motor at variable speeds is fed from a supply tank or box which is so associated with the driving means that in the actuation of the spiral conveyor a certain amount of independent or shaking movement is also imparted or transmitted to the feed box which in turn is communicated to the powdered material therein. In addition the feed box may be and preferably is provided with internal means arranged with advantage in contact with the spiral conveyor whereby additional liveliness is imparted to the material and adhesion thereof to the walls of the charging box is minimized.

The invention also consists in the improved devices for feeding finely divided material, hereinafter more fully described and set out in the accompanying claims.

Referring now to the drawings Flgures l and in show in longitudinal vertical section (broken in the length for convenience) one construction of pipe casting apparatus with associated coating devices according to the invention; the former figure showing the charging end and the latter figure the remote end.

Figure 2 is a section, to a larger scale, of parts located to the left hand end of Figure 1.

Figure 3 is a detail as seen in a section on the line 3-3 of Figure 2. V

Figure 4 is a cross-section on the line ll of Figure 2.

Figure 5 is a cross-section through the pouring trough shown in Figure 1, to an enlarged scale.

Figures 6 and 'l are under-side plan and crosssectional views respectively of a nozzle or delivery end.

In carrying the invention into eflect in one form, by way of example, the drawings show a practically tested form of this invention applied to a pipe spinning machine. This has a rotating and longitudinally movable mould a supplied from a stationary pouring trough b and a helical conveyor 0 arranged to revolve inside a tube or conduit d preferably of steel taking its supply through cut-away portions from a feed box e at thetop end of the machine. The tube d is suitably arranged within and underneath the cast iron liners f fitted within the pouring trough b down which the molten metal runs to the mould, and terminates-in a perforated or nozzle region.

The feed box e is attached flexibly at g to a hollow supporting member h at the end of the pouring trough, and a bracket hi also attached at that region is used to support the motor 1 and driving gear is. At its opposite end the feed box is supported by means of spring metal strips 1 resting on the cuts of a nut 11 forming the attachment of the helical conveyor 0 to the driving shaft 701. Steel balls I: are embodied in each cant so as to reduce wear at this point. Consequently on rotation of the conveyor a vibratory or shaking movement is transmitted to the feed box thereby ensuring movement of the ferrosilicon or other powder inside the feed box to maintain a constant feed thereof to the conveyor. To the same and spring steel wipers m are in addition arranged in close proximity to the side walls e1, er of the feed box, the lower extremity preferably of each wiper being fitted with a steel ball ml or other suitable brushing or wiping body. This body engages with the turns or coils of the conveyor 0 thereby receiving and imparting also to the wipers m a reciprocating or swinging motion as the conveyor revolves, the effect of which motion is to cut the fllm of the powder tending to adhere to the walls of the box and facilitate its falling down on to the spiral convevor.

Unlike most spiral or helical conveyors, the one proposed for use here has preferably no central core but consists merely of a stiff helical spring; as an example, to the following dimensions%" outside diameter, pitch, and constructed of square wire. This size, however, would obviously be varied for different sizes of apparatus. w/

The feed speed of the conveyor may be varied as may be required through suitable reduction gearing, a rheostat or other control being to that end incorporated with the motor to vary the speed of the latter.

In operation, molten metal is poured more or less in the usual manner from a. tilting ladle n down a fall spout 0 and along the pouring trough b for delivery over its end hi on to the mould interior. As soon as the molten metal reaches the delivery end of the trough or in any other suitably timed relationship the motor i is started up at the requisite speed causing the conveyor 0 to revolve and deliver the ferrosilicon or other powder along the tube and deposit said powder through holes d1 at the delivery end or nozzle of the tube on to the interior of the mould preferably immediately in advance of the deposition of the molten metal on the said mould. According to demand and the speed imparted to the helical .conveyor a corresponding variation in the quantity of ferrosilicon or other powder may be delivered through the perforations or outlets of the tube at the casting end of the trough. With advantage the feed box is provided with a perforated grid ea at the top to prevent ingress of foreign material.

During working conditions, it is sometimes found necessary to re-set the trough down which the molten metal flows and for this reason the powder supply apparatus is by preference attached as shown directly to the cast iron trunnion arrangement p forming or associated with the fixed and b: of the pouring trough, so that the trough together with the powder supply apparatus is adjusted as found necessary as one unit, and individual settings become unnecessary.

To protect the apparatus during casting operations the motor and feed box may be suitably housed in any desired manner.

The-foregoing description refers to apparatus essentially suitable for that method of working in which the pouring in of the metal occurs immediately after the coating of a portion of mould with the powdered material; in other words, the spiral laying of material and of molten metal follow immediately one after the other. Naturally the invention is not limited to this specific method but can also be practised otherwise, e. g. in connection with the dump-trough charging method, the coating being laid in some such cases during the positioning of the charging trough in the -mould prior to the dumping of the charge. 1

Having now described our invention, what we claim as new and desire to secure by Letters Patent is:-

1. A powder distributor comprising a tubular conduit extending along a. metal pouring trough .and contained within the body thereof, said conduit having a perforated end portion exposed in proximity to the pouring end of the trough,

means for introducing powdered material into its opposite end, a rotatable coreless helical coil member for feeding said material along said conduit to said perforated end, and means for rotating said coil member.

2. A feeding device for finely divided material, comprising a container having downwardly convergent lateral walls. Archimedean screw meanspassing through said container between. the proximate base regions of said walls, a conduit embracing said screw means and extending from opposite ends of said container, and dependent agitator elements secured inside said container and having a wiping action upon said walls and having -free extremities resiliently contacting with said screw means.

3. In a pipe casting machine comprising a rotatable mould and a runner trough adapted to deliver molten metal progressively into the rotating mould, the combination therewith of a container for finely divided mould coating material, a conduit from said container secured to and supported by the trough so as to be relatively longitudinally movable with respect to the mould to the same extent as is the trough, a delivery nozzle to said conduit for said finely divided material so located with respect to the delivery end of the trough and the inner surface of the mould as to discharge the material on to those portions of the mould which by the rotating movement of the mould and the simultaneous relative retraction of the trough are, shortly after the application of the coating material, contacted by the molten metal issuing from the trough, a rotatable coreless helical coil screw extending along said conduit from the interior of said container to the region of said nozzle, for delivery of the material thereto, and agitational means at the outer region of said conduit for ensuring flow of the material thereinto.

4. Apparatus according to claim 3 comprising means for driving said screw, vibratory means rotatable with said driving means and wherein said container is attached through flexible means to said trough, and means are provided operatively connecting said vibratory means with said container.

5. Apparatus according to claim 3, wherein said screw extends through the base of said container and dependent flexible members are provided within said container attached at upper ends to upper regions of said container and co-operating at their free extremities with the coils of said screw.

6. Apparatus according to claim 3 comprising means for driving said screw wherein said conduit and screw extend together through said container, said driving means being coupled to the screw externally of said container through rotational means adapted to agitate mid container by engagement intermittently with means connected thereto.

7. Apparatus-according to claim 3, wherein said conduit extends through said container near its base with lateral openings admitting said material to said screw, and comprising spring wipers anchored within said container and brushing the lateral walls thereof, said wipers com- WILLIAM RIDLEY.

PERCY HUTCHINSON WILSON. 

